Why does this happen!?? :-(?

I got a tattoo 2 weeks ago on the side of my left foot of swirly designs & three flowers. The flowers are JUST starting to peel......the one has pretty much peeled and like, ALL the purple ink peeled off with it too!! You can hardly see the purple and it looks so faded :-( This didn't happen with my other tattoo!! Is it the area because the skin's more thin there? I am going to get a touch up but I don't want the same thing to happen again when I touch it up! How come the ink won't stay in? :-( :-(